Supporting-slab for plaster.



' citizen of the United States, residing city of St. Louis, State of Missouri, 1

J j IT D. STA S PATENT OFFICE. j

FRANKA. smaller, or STeLOUIS, MISSOURI.

S UF PQRTlNG-SLAB FOR PLASTERL ,No'. 815,751. r

' Application filed February]6,1905. seizure. 245,321.

To (/I/ZZ whom, it 7mm concern:

Be it known that I, FRANK A. SEIFERT, a at the ave invented a certain new and useful Supporting- S'lab for Plaster, of which the following is such a full, clear, and exact description as will enable anyone skilledin the art to which it ap ertains to make and use the same, reference eing had to the accompanying drawings, formlng part of this specification.

. The object of my invention is to provide a supporting-slab for plaster, which can be nailed to the studding or joist in place of the ordinary lathing,s as to form a combined sheathing and lath.

, I am aware'that heretofore wooden slabs have been used for-the aboye purpose and pro vided with keyways orgrooves for the reception of locking-tongues of plaster. In suchconstruction, however, the wooden slab is expansible-that is, it swells and contracts owing to the amount of moisture contained withinthe slab, On this account the plaster tongues extending into the keyways are soon broken ofhso that the plaster readily comes loose from thesupporting-slab The object I slab which of In invention is to )rovide a su ortin D tions. 7

1n the accompanying drawings, which illustrate a supportingslab made in accordance with my invention,-Flgure 1 is an elcvation, and Fig. 2 a"cross-soction.

lnke .m'arks ol reference-refer to similar parts in both views of the drawings.

I The slab 5 is formed of plaster-of-paris and suitable fibrous materialsuch, for instance, as hcmphber. .l also prefer to use woodulp in the formation ot-thc slab; so as to.

lighten the resultingarticle. The essential ingredients, however, are theplaster-ofaris and a suitableiiber to render the re'su ting slab su'lliciently strong and durable. With in the slab jl'embed a wire-netting 6, the object of which'is to strengthen the slab and are all inclinedin the same direction and are prevent its being broken, especially along the weakened 'lines formed by the keyways, which will be hereinafter described. Formed in .the sun" ace of the slab 5 are a number of undercut keyways 7. These keyways, as will be readily seen from Fig. 2 of the drawings,

widest/at their outlet, so that they can read- X v Q will overcome the above o.bjec- Specification of Letters Patent.

be done the wire-netting 6 while of sufiicient .tensile stren th to strengthen the slab must ding or joist, and'the plaster 11 is ap lied directly to it, as in the case of ordinary athin sa-id key-ways.

. Patented March 20, 1906.

ily be molded in a solid mold. The por; 53 tions between the keyways 7 in place of being made fiat are slightly rounded and inclined, as shown at 8, so as to prevent the formation of an. acute angle, which would readily be broken off in'handling the slab. Crossin the keyways 7 are strengthenin -ribs 9. ese ribs 9 areplaced the same istance apart as the normal distance between the joist or studs in the structure in which it is intended to use the slab. The ribs 9 are provided with depressions 1.0 to enable the laster to ad-- here more firmly to the said 11 s. In using the slabs it is necessary to divide the same by means of a saw, and in order that this may be suflicient y soft'to be-readily severed by the use of a saw. In using my sup ortin' slab the same is nailed directly to t e stu Before applying the plaster, however it is necessary to'size the surface of the slab 5].! This may be done with any ordinary sizesuch, for instance, as a glue or a rosin size. i

ljlaving fully described my invention, what I claim as new, and desire to secure byLetters Patent of the United States, is-

1. A sup orting-slab for plaster formed'o'f inexpansib e material and provided with a plurality of lon itudinally'extending key ways and strengthening-ribsextending across 2. A sup orting-slab forlaster formed .90 with a plura ity of parallel un ercjut keyways, said keyways being all inclined in the same direction and being widest at their outlet.

A supporting-slab for plaster formed of plaster-of-paris and fibrous material and havmg a wire -netting embedded therein, and having a plurality of parallel undercut keyways formed in the face thereof, said keys ways being all inclined in the same direction and being widest at their outlet.

In testimony whereof I have hereunto set my hand and affixed my seal in the presence v of the two'subs'cribing witnesses FRANK A. SEIFERT. [L. 8.1 

